An audio port in a personal computer and a mobile electronics device is very rarely used for data communication and power transferring. As a modern electronics device is getting smaller and more powerful, it can be made with more and more functions, due to the portability requirement. Most of them have very limited external interfaces to communicate with a peripheral device. Besides universal serial bus (USB) and wireless interface, an audio port or interface provides a very non-expensive approach for a host device to communicate with a peripheral device.
In the mean time, to simplify the design of both host and peripheral devices and reduce the cost; it is desirable to transfer power from the host device to the peripheral device through the audio interface. Conventional systems use one channel of stereo audio port to provide power to a peripheral device and the other channel used for data communication. Limited to the driving strength of audio port, one audio channel is not sufficient to provide enough power for many applications.